34<^ ESSAYS AND OBSERVATIONS 



fp'ir, nitri, after a pretty ftrong efFervef^ 

 cence, we fliall find a metallic powder at 

 the bottom. 



IV. Some metals diflblved in an acid 

 liquor may be precipitated thence by 

 another metal or metallic, ftony or cal- 

 carious fubltance, capable of being dil- 

 folved in the fame menftruum. 



Under the head of folution, I had oc- 

 cafion to adduce a well known inftance, 

 to fhow that a menftruutti having diflblved 

 one body, will fucceffively diflblve feve- 

 ral others in a certain order. I am obli" 

 ged to mention the fame again, as a con- 

 firmation of the prefent remark. If pure 

 filver is diflblved in proof aqua fortis, and 

 the folution diluted with fair water, the 

 filver will be precipitated by copper, the 

 diflfolved copper by iron, and that by 

 lirae-ftone. This however is not the 

 fole infl:ance of this way of precipitation : 

 Others may be found. The fublimate 

 corrofive mercury may be jufl:ly looked 

 upon as a folution of quick-filver in the 

 acid of fea fait or aqiia regia^ brought in- 



to 



